Effect of semduramicin, salinomycin, and monensin on performance, shank pigmentation, and coccidial lesions in broiler chickens in floor pens.

The effects of 25 ppm semduramicin, 66 ppm salinomycin, 110 ppm monensin, and unmedicated treatments on performance, shank pigmentation, and coccidial lesion scores in broiler chickens were evaluated in two floorpen trials in the United States. On day 24 of each test, birds in each treatment were inoculated via the feed with a mixture of recent field isolates of Eimeria spp. at a dose rate calculated to provide 2 x 10(5) E. acervulina, 3 x 10(4) E. maxima, and 2 x 10(4) E. tenella sporulated oocysts per bird. Weight gain and feed conversion were significantly (P < or = 0.05) improved in the semduramicin-treated broilers in comparison with the monensin-treated and unmedicated broilers. These performance variables for the salinomycin-treated birds were intermediate between the semduramicin- and monensin-treated birds. Shank pigmentation scores were significantly (P < or = 0.05) improved in the three anticoccidial treatments compared with unmedicated birds, with the highest scores (P < or = 0.05) occurring in the semduramicin-treated broilers. Semduramicin was more efficacious (P < or = 0.05) than salinomycin in controlling upper intestinal lesions and more efficacious than monensin in controlling mid-intestinal lesions. All three drugs were comparable in controlling lesions in the ceca.